This invention relates to a battery backup circuit for maintaining uninterrupted operation of a microcomputer, which is normally energized by a-c line voltage, when a power outage or low voltage transient occurs.
An operating potential of fixed magnitude must be continuously applied to a microcomputer or microprocessor to ensure proper operation thereof. If there is a power loss, even though momentary, the operation will be deleteriously affected. For example, the memory devices may store false information that was not there originally. Moreover, when power is restored, the microprocessor could receive erroneous command signals. Hence, it is most desirable that a battery backup system, which automatically activates in response to a loss of a-c line voltage, apply battery power to the microprocessor before it adversely suffers from the line voltage loss. This is achieved by the battery backup system of the present invention, and yet the system is of relatively simple and inexpensive construction.